A sheep in wolf's clothes: can neutrophils direct the immune response?

The intercellular transfer of cell membranes and integral membrane proteins has been reported for a wide variety of cells, including cells involved in the immune response, and the passively acquired proteins can alter recipient cell function. Cell membrane transfer can occur by a variety of mechanisms and conditions such as inflammation, cell death, or cell stress increase the release of membrane fragments by donor cells. This review focuses specifically on neutrophils as the recipients of cell membranes and integral membrane proteins. Neutrophils are often the first cells recruited to sites of inflammation where there is ample opportunity to acquire membrane proteins shed by a variety of cells. Our recent investigations have confirmed that bovine neutrophils have an impressive capacity to rapidly acquire membrane proteins from necrotic and apoptotic cells. Furthermore, these acquired proteins can alter neutrophil phenotype and function and we hypothesise that they may enhance their capacity to integrate innate and adaptive immune responses. The implications of these alterations to neutrophil function are discussed within the context of vaccine and novel immune therapy design.